i dunno if he is weaker, he can throw around bijuu sized beings, and if naruto cant transfer chakra through chakra cloaks then sasuke gets demoted back to midget susanoo
If Kurama is indeed gone for good then he'll obviously get a power-up of some sort to combat Madara. He'll end up stronger then he was before.
Basically, it potentially could be the biggest arsepull of a powerup in the series history. And Naruto won't get shit for it, people will just be "Main Character, his development is allowed to be ridiculous"